By incorporating low-cost components from consumer electronics into their confocal microscope design, researchers have achieved a 100-fold increase in the image acquisition speed of the instrument.

Motivated to visualize calcium and neurotransmitters being released in brain
tissue, which takes mere milliseconds, researchers from the University of
Leicester, UK, have developed a “bolt-on” confocal system to improve the
acquisition time of an existing camera and microscope. Using a low-cost
light source, the new instrument matches the resolution of traditional
confocal instruments but has a 100-fold increase in acquisition speed,
sufficient to image high-speed calcium signaling in rat neurons.

By incorporating low-cost components from consumer electronics into their confocal microscope design, researchers have achieved a 100-fold increase in the image acquisition speed of the instrument. Source: PLoS One

Studying molecular events in live cells has been challenging with conventional
laser-scanning confocal microscopes. These microscopes work by sweeping a
laser across the sample and collecting the light it emits filtered through a
single pinhole that blocks unfocused light from other parts of the sample.
While high-resolution images are attainable with this method, they can take
as long as two seconds to produce.

Described in a paper published August 24 in PLoS One (1), the new
instrument incorporates a digital micromirror device (DMD)—an inexpensive
component found in consumer electronics like televisions and projectors— to
define the patterns of sample illumination and detection. The DMD is an
array of 1024 by 768 tiny mirrors that can each alternate between “on” or
“off” and then can collect the light emitted from the sample.

The DMD used in the new instrument works on the same principle as the spinning
disk technique—which uses an array of multiple pinholes arranged in a spiral
that is spun to fill the image of a sample—except that the mirrors serve as
pinholes. More importantly, the DMD is programmable. “You can choose the
level of resolution that you want,” said study author Nicholas Hartell. “If
you want something that’s very high resolution, you need to go a bit more
slowly, but if you don’t mind losing a bit of resolution you can go
incredibly fast.”

Although other groups incorporated DMDs in confocal instruments, none has
reported major gains in image acquisition speed. In contrast, “we’ve used a
system that allows us to turn the mirrors on and off much more rapidly,”
said Hartell. Also, the optical configuration of mirrors that collect
emitted light in the new instrument does so more efficiently than a
lens-based system.

The new microscope is also relatively low-cost, partly because its light
source, light-emitting diodes, is far less expensive than the lasers used in
standard instruments. “Whereas, a bank of different wavelength lasers would
cost tens of thousands of dollars, we can do [the light source] for probably
about $100,” said Hartell.

In the new microscope, the detector now limits image acquisition. While
Hartell’s group uses a charge-coupled device camera, a complementary
metal-oxide semiconductor camera can be easily swapped in for an additional
10-fold boost in imaging speed. Now, his group is working with the
University of Leicester’s Space Research Centre to incorporate an even
faster detector, and he expects results within several months. Hartell’s
team is also working to commercialize their instrument and have a potential
partner to license the technology.